The hostel blaze that killed 15 backpackers, including seven young Britons, probably started in several locations, an expert told an Australian murder trial today.

Dr John DeHaan is one of the final prosecution witnesses in the trial of drifter Robert Paul Long, 38, who denies arson and murder at the Palace Hostel in Childers, 190 miles north of Brisbane.

A leading US forensic scientist, Dr DeHaan said the blaze started in the TV room and spread to other rooms.

"Based on the time intervals and the observations of the behaviour of the fire it was my opinion that the fire started in at least two, possibly several, locations in that room," he told Brisbane's Supreme Court.

He said the heat inside the room became so intense that everything, including furniture, wall paint and carpet, burst into flames at the same time.

The trial has already been told a burning bin covered by a lounge cushion was taken out of the TV room before the fire.

A backpacker had told the court he removed the smouldering cushion and a man, whom he alerted to the fire, took the bin outside.

The court has been told a fire broke out a short time later forcing backpackers to escape the century-old building.

Dr DeHaan said he found evidence in the TV room of a "flashover" - where the build-up of heat and gas becomes so intense it causes everything to ignite at once.

"It generates enough radiant heat to rise other items in the room to their ignition point," Dr DeHaan said.

He said a flashover could be described by an onlooker as a room "fully engulfed by flames".

"In this case the floor coverings had been destroyed, the surface of the walls had been attacked to floor level and the windows had signs of flames up the walls outside," Dr DeHaan said. The seven Britons who died in the blaze were: Mike Lewis, 25, from Bristol; Gary Sutton, 24, from Bath; Sarah Williams, 23, from Aberfan, South Wales; Natalie Morris, 28, from Cefn Coed, South Wales; and Melissa Smith, 26, from Thatcham, Berks, Claire Webb, 24, and Adam Rowland, 19, from England .